1. Field of the Invention
The present invention relates to an ink, an ink-jet recording method employing the ink, and an instrument employing the ink. More particularly, the present invention relates to an ink, an ink-jet recording method, an ink-jet recording unit, an ink-jet recording apparatus, and an ink cartridge which allow recording in high resolution and high quality not only on coated paper prepared specially for ink-jet recording but also on non-coated ordinary paper generally used in offices and homes such as copying paper, reporting paper, notebook paper, letter paper, bond paper, continuous business form paper, and the like.
2. Related Background Art
Various compositions of inks have been reported for ink-jet recording. In recent years, research and development are comprehensively conducted regarding inks from various aspects of compositions and physical properties of inks for the purpose of achieving satisfactory recording on ordinary paper such as copying paper, reporting paper, notebook paper, letter paper, bond paper, continuous business form paper, and the like.
Conventional inks contain generally a high-boiling organic solvent like glycol for retardation of premature drying and prevention of clogging of ink. If such an ink is used for recording on highly sized ordinary paper, the ink does not readily permeate into the interior of paper and does not dry rapidly, which causes insufficient fixation of ink, and which in inconveniences such as staining of a finger and blurring or scratching of letters upon touching a recorded matter.
To offset the inconvenience, Japanese Patent Application Laid-Open No. 55-29546 discloses a method of adding a large amount of surfactant to the ink to increase permeability of ink into the interior of paper. In this case, however, troubles are encountered such as frequent occurrence of running or feathering of ink depending on the kind of paper; and retardation of ink ejection in ink-jet recording caused by backward movement of ink from the orifice-outlet face, or wetting of the entire orifice-outlet face depending on the structure of the head.
Further, Japanese Patent Application Laid-Open No. 56-57862 discloses a method of making the pH of ink strongly alkaline. Such an ink is disadvantageous in that the ink is dangerous to humans when touched with a finger and the ink is unsatisfactory in occurrence of feathering and insufficiency of drying property on paper employing a certain kind of sizing agent, e.g. neutralized paper.
In spite of the aforementioned and other improvements, no ink is known that is free from the problems of feathering, lack of drying property, danger to humans, and occurrence of clogging and so forth.